A local area network (LAN) is largely classified into a wired LAN and a wireless LAN (WLAN). The WLAN is a communication method performed in a network using an electric wave rather than a cable. With an advent of the WLAN, anticipation is growing for the WLAN to resolve cabling-related issues, such as installation, maintenance, or movement of cables. Moreover, as a number of mobile users are increasing, a demand for the WLAN is also set to surge.
A configuration of the WLAN includes an access point (AP) and a station (STA). The AP refers to equipment for transmitting an electric wave to enable WLAN users within a transmission distance to connect to the Internet and use a network. The AP functions as a base station (BS) of a mobile phone or a hub of a wired network.
A basic building block of an Institute of Electrical and Electronics Engineers (IEEE) 802.11 network is referred to as a basic service set (BSS). The IEEE 802.11 network includes an independent BSS in which STAs in a BSS perform direct communication with one another, an infrastructure BSS in which an AP is used during a process in which an STA performs communication with STAs internal or external to a BSS, and an extended service set (ESS) in which BSSs are connected to one another to expand a service area.
In a next generation WLAN system, an AP simultaneously transmits a data frame to at least one STA in a multiple input multiple output (MIMO) pairing.
In the WLAN system, when an AP and/or STA transmits a frame to a target receiver AP and/or STA, information on a channel to be used may be obtained through channel sounding. A process in which a transmitter requests, from a receiver, channel information to be used for frame transception, and the receiver estimates a channel and sends a feedback on the channel information to the transmitter is performed prior to the frame transception.